Percentage Calculator

Calculate percentages, increases, and decreases instantly.

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Everything You Need to Know About Percentages

Formulas, examples, and practical applications for everyday life.

What is a Percentage?

In mathematics, a percentage is a number or ratio expressed as a fraction of 100. It is often denoted using the percent sign, "%". For example, 45% (read as "forty-five percent") is equal to 45/100, or 0.45. Percentages are used to express how large or small one quantity is relative to another.

The Basic Formula

Percentage = (Part / Whole) × 100

Use this to find what percentage one number is of another (e.g., 20 is what % of 50?).

Percentage Change

%Δ = ((New - Old) / Old) × 100

Used to calculate growth, inflation, discount rates, or price changes.

Real-World Applications

How to Calculate Percentage Increase

To find the percentage increase between two numbers, subtract the original number from the new number. Then, divide that difference by the original number. Finally, multiply by 100.

Example: Rent Increase

If your rent goes from $1,000 to $1,200:

  1. Find the difference: 1,200 - 1,000 = 200
  2. Divide by original: 200 / 1,000 = 0.2
  3. Multiply by 100: 0.2 * 100 = 20% increase.

Using an online calculator like N28 helps avoid errors in these steps, especially when dealing with complex decimals or reverse calculations.

Common Percentage Questions

Expert answers to the most frequent queries about percentages.

How to calculate percentage?

To calculate X% of Y, use the formula: (X / 100) * Y. For example, to find 20% of 50: (20 / 100) * 50 = 10.

How to calculate percentage increase?

Subtract original value from new value, divide by original value, then multiply by 100. Formula: ((New - Old) / Old) * 100.

How to calculate percentage decrease?

Subtract new value from original value, divide by original value, then multiply by 100. Formula: ((Old - New) / Old) * 100.

What is 20% of 150?

20% of 150 is 30. Calculation: 150 * 0.20 = 30.

How to find what percentage one number is of another?

Divide the part by the whole and multiply by 100. Formula: (Part / Whole) * 100. Example: 25 is what % of 100? (25/100)*100 = 25%.

How to calculate a discount?

Multiply the original price by the discount percentage (as a decimal) to find the savings. Subtract savings from original price to find the final price.

How to calculate sales tax?

Multiply the retail price by the tax rate. Example: $100 item with 5% tax = 100 * 0.05 = $5 tax.

How to calculate a tip?

For a 20% tip, multiply the bill amount by 0.20. For a 15% tip, multiply by 0.15.

What is 50% of 100?

50% of 100 is 50. This is exactly half.

What is 10% of 500?

10% of 500 is 50. Calculation: 500 * 0.10 = 50.

How to convert fraction to percentage?

Divide the top number (numerator) by the bottom number (denominator) and multiply by 100. Example: 1/4 = 0.25 * 100 = 25%.

How to convert decimal to percentage?

Multiply the decimal by 100 and add the % sign. Example: 0.75 becomes 75%.

What is 1/2 as a percentage?

1/2 is equal to 50%.

What is 1/3 as a percentage?

1/3 is approximately 33.33%.

What is 1/4 as a percentage?

1/4 is equal to 25%.

What is 3/4 as a percentage?

3/4 is equal to 75%.

What is 100% of a number?

100% of a number is the number itself.

What is 200% of a number?

200% of a number is double that number.

How to find the original number before an increase?

Divide the new value by (1 + percentage as decimal). Example: If 120 is after a 20% increase, original = 120 / 1.20 = 100.

How to find the original number before a decrease?

Divide the new value by (1 - percentage as decimal). Example: If 80 is after a 20% decrease, original = 80 / 0.80 = 100.

Can percentages be greater than 100?

Yes. 150% means 1.5 times the original amount. This often happens with growth metrics.

Can percentages be negative?

A percentage change can be negative (indicating a decrease), but a percentage of a physical quantity is usually positive.

What is a percentage point?

A percentage point is the simple arithmetic difference between two percentages. E.g., moving from 4% to 5% is a 1 percentage point increase.

What is a basis point?

A basis point is one hundredth of one percent (0.01%). It is commonly used in finance.

How to calculate profit margin?

Profit Margin = ((Revenue - Cost) / Revenue) * 100.

How to calculate markup?

Markup = ((Sales Price - Cost) / Cost) * 100.

How to calculate percentage error?

Percentage Error = |(Approximate Value - Exact Value) / Exact Value| * 100.

What is the percent symbol?

The percent symbol is %.

How to type percent symbol on keyboard?

On standard US keyboards, hold Shift and press 5.

Is this percentage calculator free?

Yes, N28.net tools are completely free to use.

Do I need to install an app?

No, this calculator runs directly in your web browser.

Does this work on mobile?

Yes, N28 is fully responsive and works on iPhone and Android.

How accurate is this calculator?

It uses standard JavaScript floating-point math, which is precise enough for all standard financial and everyday calculations.

Why use an online calculator?

It saves time and prevents mental math errors for complex percentage changes or reverse calculations.

How to calculate body fat percentage?

Body fat is typically estimated using measurements of the neck, abdomen, and height, varying by gender. Specific formulas like the US Navy Method are used.

How to calculate grades as percentages?

Divide your score by the total possible score and multiply by 100. Example: 45/50 = 0.9 = 90%.

How to calculate percent difference?

Find the absolute difference between two numbers, divide by their average, then multiply by 100.

What does 'per cent' mean?

'Per cent' comes from Latin 'per centum', meaning 'by the hundred'.

How to calculate interest rate?

Interest = Principal * Rate * Time. To find the rate, rearrange to Rate = Interest / (Principal * Time).

What is reverse percentage?

Reverse percentage involves working backwards from a final number to find the original number, often used to find pre-tax prices.